Does the yob, always a good cost effecient option when it comes to lenses. I find sigma does ok with its 10-20 2.8 and its 24-70 2.8 along with the aforementioned 70-210 2.8. Stear clear of the 50-500, the 80-400, and the 300-800, imho, they make them simply cause...well they can [img]/ubbthreads/images/graemlins/smile.gif[/img]

Shouldn't have any problems with the glass, much more inexpensive then the Canon and the L's are clearly better preferrably with the IS, but the non IS version still a great chunk of glass.....and the 70-200 F4 L isn't so bad either if your looking to save some dollars and get the quality.

I have he Sigma 70-200 2.8 HSM and it is a fantastic lens. It has been rated almost in a dead heat with the Canon 70-200 2.8 L lens. Now you say 210 rather than 200 and I don't know if we are actually talking about the same lens. Are you talking about 200 or 210 and if 210, then would it be a used lens?
Cheers,
rfs